Hello! I have been through your question. Related your concern you should know that metronidazole crosses the placental barrier and its effects on the human fetal organogenesis are and not known and it is belong for teratogenic effects in pregnancy category B. The use of metronidazole during pregnancy is controversial, especially during the first trimester and I know that metronidazole is mutagenic in vitro and carcinogenic in rodents, but these concerns have not been shown in humans. In some reproduction studies have been performed in rats, rabbits, and mice at doses similar to the maximum recommended human dose and there was no evidence of harm to the fetus due to Metronidazole as well in most studies did not show an increased risk for congenital anomalies or other adverse fetal outcomes following metronidazole exposure during pregnancy. Although, using metronidazole in the 2nd and 3rd trimesters may be acceptable ( according CDC) if other treatments have failed. For other indications, metronidazole should be avoided during pregnancy whenever possible, with use occurring only after careful assessment of the potential risk. So ,I think you should ask first your doctor if exist any other alternative to treat your infection before using metronidazole. I hope my answer help you. I wish you a quick recovery.